Optimization of Solar Kiln for Drying Wood

Theoretical investigation of the physical process of solar drying of timber based on conventional heat and mass transfer equations is presented. The governing equations and boundary conditions of the mass diffusion through the wood timbers are derived; also the governing equations of the components of the solar kiln are presented. The finite difference technique is used to solve the set of these equations by means of a simulation program that is based on object-oriented approach. The simulation program is used to investigate the effect of several design parameters on the drying rate and duration of the wood timbers in order to accomplish the drying process with minimal drying defects. These parameters include the ventilation conditions that control the drying schedule inside the solar kiln, wood volume as a ratio to the solar kiln absorber area, wood timber thickness, season of drying, the drying air velocity, and the stresses that formed on the timber boards due to drying with these several parameters, leading to derive the limit of damage for a selected local wood type. The selected local wood type is Casuarina, which is common in Egypt, and it is commonly used in many simple industries.